How hard would a puck have to be shot to be able to knock the goalie into the net?

[goalguard]

Most of us fans have a six-month wait before we see our teams skate again. But you can stay mentally sharp, this week at least, by checking out my favorite non-hockey site: http://what-if.xkcd.com/

This week it carefully calculates the question posed by the title of the thread (and as a bonus, it describes the toll that such a shot would take on the goalie and how much you could tilt a rink till all the players slid to the low end).

If you're killing time till the first game next October, browse back to earlier posts that answer such pressing questions as: how many b-b guns would it take to stop a locomotive; what if you tried to fly a Cessna in Venus's atmosphere (bad things); and how long could you survive in a cooling pond for spent nuclear rods?

One-hundred and eighty days to go till hockey starts up again. And counting. Slowly.

[FlagDUDE08]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

If you're shooting against Ben Scrivens, not very. We were able to do that in 07-08.

[Tipsy McStagger]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

Most of us fans have a six-month wait before we see our teams skate again. But you can stay mentally sharp, this week at least, by checking out my favorite non-hockey site: http://what-if.xkcd.com/

This week it carefully calculates the question posed by the title of the thread (and as a bonus, it describes the toll that such a shot would take on the goalie and how much you could tilt a rink till all the players slid to the low end).

If you're killing time till the first game next October, browse back to earlier posts that answer such pressing questions as: how many b-b guns would it take to stop a locomotive; what if you tried to fly a Cessna in Venus's atmosphere (bad things); and how long could you survive in a cooling pond for spent nuclear rods?

One-hundred and eighty days to go till hockey starts up again. And counting. Slowly.

Have you watched Problem Child 3 lately?

[Dirty]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

This proves once and for all that physics is lame.

[beaverhockey]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

Sounds like a job for Mythbusters!

[MavHockey14]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

All I know is only WCHA teams could do it.

[MinnesotaNorthStar]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

You must shoot it "Fulton Reed hard"

[FlagDUDE08]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

All I know is only WCHA teams could do it.

Bull****. I've seen an EZAC team do it.

[bigblue_dl]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

I went to school so I wouldn't have to read about Physics anymore...

[DoorCtyBadgers]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

that kid from the mighty ducks hockey team got laid out a few times

[FreshFish]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

I don't think it is possible to shoot a puck hard enough to knock the goalie into the net. Any puck shot that hard would probably put a hole through him first instead.


Basic physics: momentum = mass times velocity. Since the puck has so little mass relative to the goalie, the puck's velocity would have to be extremely high. At that speed, it would be like a cannonball.



PS If that's what the link in the original post said, my apologies, my browser security settings won't let me open that link.

[Terrance]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

Lots of factors here. Are we talking the puck knocks him over onto his back or he just slides into the net standing on his skates? If the goalie is standing on his skates and they are parallel to each other and perpendicular to the ground aiming directly into the net, it might not take as much as you'd think to slide him into the net. Basically kinetic energy of the puck (.5*mass*velocity^2) must equal the work done by friction between the ice and the skates throughout the distance of the slide (coefficient of friction*mass of the goalie*distance) ignoring air resistance (which I think is comparatively negligible). The puck would also need to hit him at his center of gravity and at a 90 degree angle to his body. If you want to account for a glancing hit, I think you would just multiply the puck energy by sin(angle).This also assumes the energy of the puck isn't absorbed by the clothing/pads/body (which it definitely would be). If we assume 60% of the energy of the puck is absorbed (I have no idea what the actual percentage would be, probably more like 80-90% since that's what they're made to do) just multiply the puck energy by (1-.6) and you can do some algebra (yes math) to find the velocity. I haven't done this type of thing in a while but I'm pretty sure this is right. Though the numbers seem to be coming out to about 16 miles/hour so that seems low. Then again, I'm not sure about the coefficient of friction or the percentage of energy absorbed and that's pretty important.

[UML]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

Wicked hard.

[goalguard]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

I don't think it is possible to shoot a puck hard enough to knock the goalie into the net. Any puck shot that hard would probably put a hole through him first instead.

Basic physics: momentum = mass times velocity. Since the puck has so little mass relative to the goalie, the puck's velocity would have to be extremely high. At that speed, it would be like a cannonball.

PS If that's what the link in the original post said, my apologies, my browser security settings won't let me open that link.

You can get to the link and the analysis by googling "what if xkcd" The physics guru says the speed would have to be between mach 2 and mach 8, depending on certain assumptions. The puck would then burst apart inside the goalie.

I don't have the rule book in front of me, but I think this would count as a goal as it would happen so fast, the ref wouldn't even have the time to formulate the intent to whistle the play dead (not to mention indicating the same for the goalie).

[FlagDUDE08]

Re: How hard would a puck have to be shot to be able to knock the goalie into the net

You can get to the link and the analysis by googling "what if xkcd" The physics guru says the speed would have to be between mach 2 and mach 8, depending on certain assumptions. The puck would then burst apart inside the goalie.

I don't have the rule book in front of me, but I think this would count as a goal as it would happen so fast, the ref wouldn't even have the time to formulate the intent to whistle the play dead (not to mention indicating the same for the goalie).

If a puck splits and both pieces go in, the goal counts. Otherwise, play is blown dead. It did happen in I think juniors (or was it college?) where a player shot the puck so hard that when it hit the post, it split in two.